Fraction-reading micrometer caliper



` Nov. 24, 1925. v R. G. NlLsoN FRACTION READING MICROMETER CALIPER Filed Nov. 14, 1921 E: EL

iam

fl il Patented lntj.

clairs sr 'rss RALPH it. NELSON, OF "LV RCESTER, MASS ACHUSETTS, .ASSIGNOR TO MILS NILSON, 0F

VGRGESTER., MASSACHUSETTS.

FRAGTION-READNG MICROMETER CALIPER.

Application filed November 14, 1921.

To o/Z yzii/H3 may coi/ccm x Be it known that l., Hanru G. NiLsoN, a citizen o1 the llnited States, residing at llorccster, in the county ot Worcestcr and State olf Mz ssachusetts, have invented a new and useful Fraction-Reading lficrometer Caliper, oi' which the followingl is a specilication.

This invention relatos to a micrometer caliper for use by machinists principally. The chiel objects are to improve the ordinary micrometer caliper on the market, Without taking any of its valuable features from it, in such Way as to provide for reading thc ordinary fractions ot an inch directly on the caliper, to provide graduations on the stationary sleeve ot the caliper in such position as to shou the oii'dinary fractions directly and 'Without Comput tion or the use ot tables, and more especially 'to guard :urainst mistakes that are possible in the use ol the ordinary caliper.

Reference is to be had to the accompany ing drawing, in which` Fig. l is a side view of a micrometer caliper with a preferred embodiment or" this invention applied tl creto, and showing it in a position 'for measuring` exactly 21 /64 of an inch; and

Fig. Q is an enlarged representation ot the surface ot the stationary graduated sleeve developed. and spread ont flat, this vieiv representiup; the entire cylindrical sui-tace.

In the use oit the ordinary micrometer caliper, is `well known, a complete turn of the thimble moves the spindle l/llO of an inch The crcuuitcrence ot the thimble is divided into twentydive divisions so that tmninp,I it one division advances or retracts the spindle t /1000 oi an inch. In other Words, as is u'ell known, the inicron'icter is constructed and calibrated to measure in thouscmlths and it is customary to translate ordinary fractions into decimal ecpiivalentsn either by lignring them out or by the use of tables and then adjusting the caliper to the proper number ot' thousandths instead of to the proper fraction ot the inch. rThis would get absolutely accurate results it it were not for 'the tact that most ot the ordinary fractions cannot be expressed in even numbers oi thousandths but the decimal must be carried out one, two or three more places. The user, therefore, has to guess at the fractional tl'iousandths and, while this is not important Serial No. 514,907.

for rough Work, it does result in variationsl per with the ordinary scale divided into' tenths on the sleeve 10 and the ordinary circular scale divided into twenty-fifths on the thiinblc l1, as described above and then divide up the cylindrical surface ot' thc sleeve into eight equal divisions circumterertially, starting with the usual zero line c. This provides a series ot longitudinal parallel lines 7) spaced equal distances apart around the circumference, and each one being spaced from the next one a distance equal to 1/8 ot the circumference. Now, it will be obvious that if the zero point c on the circular scale of the thimble of the caliper is moved from the zero line o to the nextadjacent parallel line 7) the spindle 12 will have been retracted or advanced a distance equal to l/8 ot 1,/40 ot an inch. rIhis is 1./5 of l/ll. A complete turn oi' thel thimble moves the thimble and spindle relatively alongI their axes l/lOth ci an inch as in the ordinary micrometer caliper described above. It it is desired to more the spindle l/GA oit an inch the Zero point on the rota-ry thimble will have to be turned through tive spaces I). Other distances can be found in the same Way.

These eight lines Y) are all arranged l/S ol' the circumference ot the sleeve from each other so that the thimble is turned 1/8 of a complete revolution when any point thereon passes from one ot these lines to the next one. its the thin'ible, in rotating` a complete revolution, moves lengthwise l/t() or 2,5/1000 of an inch, the thimble Will also move l/S of l/llO which is equivalentv to 1,/5 ot l/Gfl when it rotates the distance from one ot these lines to the next. In order to retract the spindle l/S ot an inch it is necessary to rotate the thiinble tive complete revolutions. lt the Zero point on the thimble coincides with the Zero point on the scale when the spindle is in contact with the anvil 13, as will be the case it' the instrument is set properly, it will be iiecessai'y to i'otate the tliinible tive complete revolutions and bring` the zero point on the thinible back to the 5th division on the zero line a., to bring the end ot the spindle just l/S ot an inch troni the anvil. Obviously to make this space l/l of an inch it is necessary to rotate the thinible 21/2 times troni Zero and that brings the ,Zero point on the thinible into registration with the line exactly opposite the Zero line a, atter rotating' the thinible twice. Tol draw bach the spindle l/S ot an inch from the anvil the thinible wouldl be rotated .l1/4r times, which would bring the Zero point on the thiiiible into registration with the second line below the line a.. ln order to get a space ot l/G-l ot an inch it is necessary to rotate the thinible 5/8 ot a revolution. To do this, the Zero point on the thinible is brought into registration with that line, that is 5/8 ot the way ai'ound the sleeve from the Zero line.

The zero line a on the usual micrometer sleeve is divided into divisions representing lOths ot an inch, each one ot them beine; 'turther divided into tour parts or -tOths by smaller division lines. 1./10 and l/l() equals l/S. Therefore, l divide the line n' into Sths very i'eadily by marking' above it divisions each representing' live lOths. I number these as shown in 2. So in mv use ot the caliper this line represents Sths ot an inch. I niark what may becalled the margin ot the sleeve at the end with the terni Sths at the lett to indicate that this line means Sths. The opposite line halt' way around represents lths and is so marked. The two lines a quarter way around in each direction represent Binds and and are marked accordingly. The other 'four lines coming` between the ones just described all represent Gflths and. are marked at the lett to show that tact. rll this is clearly shown on Fig. These. G-l-ths lines are 'turther divided, each one into Stlis, but the. iirst division on each G-lth line is, ot course.` less than an 8th troni the edge. and controlled by the traction ot an inch which themicrometer measures when the zero point on the rotary thinible points to it.

ln Fig'. :2 l have shown this entire surface developed and enlarged. The horizontal length ot this rectangular ligure is one inch. The Sths line at the center is divided by smaller divisions below it into ths of an Sth ot an inch and l've ot these divisions, therefore.y represent l/S ot an inch. This is expressed on the drawing by the numerals l to S and corresponding` division lines above the ordinary calibrations, which I retain l wish to be able to use the micrometer in the ordinary wav in which .it is now used to indicate thousandths. l divide up the lths line to show the number ot lGtlis measured by the micrometer when the Zero point on the thimble is on the lths line. This is divided into the odd numbers, oi' l to l5 inclusive, and the distance between each two is 2/16 ot an inch. The number l is located, so to speak, a haltI a space troni the lett hand line. The two 'Qnds lines ai'e divided in a similar manner and also the tour G4ths lines. Each one is designated at the lett by the proper denomination.

The divisions on these horizontal lines` indicated by the transverse marks c, constitute part of a helix traced around the sleeve by the Zero point-on the thimble as the thimble is drawn back by turning it. Part oii this helix is indicated in dotted lines in Fig. 2. As a mattei' ot tact the horizontal lines serve only to tarnish, by their junction with the. helix, the points tor use in getting' the exact measurements.r The helix`l however, does not appear on the sleeve physically except as it is represented by these divisions.

Now in using the device. it the operatoi' wishes to set the spindle l/G inch trom the anvil, the only place where he can iind a point l on any one ot the tour Gaths lines is on the one which is 5/8 wa;v around from the "i Zero 0r Sths line. To take this up in anA other manner, let it be assumed that it is desired to make the space between the spindle and anvil Q/(iaL ot an inch. Starting troni Zero the operator turns the thinible all the way around tive times which will open Ithe micrometer 1/8 ot an inch and then advances it live spaces more until the zero point thereon comes into registration with the numeral i) on one ot the Gltlis lines. Now, it he wishes to advance it l/G4 ot an inch more and bring' it to 10/64v or 5/32, he has to keep on turning the thimble in the saine direction until the zerocomes to the point numbered 5 on the 32nds line in the, lower part ot Fig. Q. In other words, he has advanced it tive spaces circuin'lerentially. Now, tobring' it to the nent (S4-tbs division, that is, ll/(ii, he advances it live more spaces to the point l] on the Glths line just above the Sths line in Fig. 2. It he turns it another five spaces he will have advanced it another 64th of an inch so that the total space between the spindle and the anvil is lQ/Gilor ji/16 and that is accomplished at the time when the zero point on the thinible registers with the division numbered 3 on the lths line.

It is believed that these illustrations are sutlieient to show the operation ot the device all` the way through. lt will be observed that the lirst division on each of the hori- Zontal lines comes at a point at a certain distance trom the circumferential line passing' through the Zero point.

These distances;

lll)

are all different on the ditl'erent lines. @n the Glths line shown at the top ot Fig'. Q., and actually just beyond the lrtt'hs line on the back otl the sleeve, is the first division. The second division comes on the zlnds line beloiv the St-hs line and, ot course, represents /tll or l/BQ and it is tive spaces circumterenti ally Afrom the one numbered l on the Glths line and l/(it trom it longitudinal ly. fllhe nent point is tive spaces turther around and is the point .numbered S on the Glths line next above the @the line and represents a space S/tl-loi? an inch. The next o-ne is numbered l on the ltths line representing l/lti ot an inch or LLt/(ill, etc.

lt can be seen, therefore, that all of the (lll-tbs and multiples thereof can be measured on this scale and the micrometer set exactly to the pointnecessary to move the spindle the desired distance, There is no computing' required nor any tables. These are entirely done aivay with and a still more important point is that the operator does not have to guess at fractions ot a thousandth as in the old system. but he gets his measurement directly on the scale and knows that it ac curate. lt is to be observed Yfurther that the micrometer of the ordinary type is used and can be employed 'for measuring' thousandths as its scale has not been modilied in any Way` Therefore, l ,eet all the adii'antages oi the ordinary micrometer caliper and provide it With very simple means by which it can be used to measure the ordinary 'fractional divisions or" an inch directly.

Although l have illustrated and described only a single form ot the invention, I am aware of the tact that modifications can be made therein by any person skilled in the art Without departing' trom the scope oit the invention as expressed in the claims. Theretore, l do noty vvish to be limited to all the details ot construction herein shoivn and described, but what l do claimis:-

l. Means tor indicating in common :traer tions ot an inch the adjust-ment ot a micrometer, the screw ot ivl'rich has the usual 4l() threads to the inch, said means comprisinp; tivo coaxial relatively rotatable cylindrical members, one being` hollow and telescoped on the other and the two being` interconnected throunh, the gauge screw so as to be relatively shifted axial-ly thereby in accord with the pitch ot the screiv upon relative rotation ot the members, the inner ot said members being; provided upon its cylindrical surface with eight lines extending longitudinally ot the cylinder and equally spaced therearound, each ot said longitudinal lines being provided with division marks, each ot said division marks being; numbered to show the numerator of the traction indicated thereby and the longitudinal lines being, severally identitied with numbers correspondiup,` respectively to the denominator ot the fractions indicated by the marks thereon, the outer member being provided at the end edge thereot overlying the inner member with a Zero mark and with a circumterential scale of gradnations, each division mark ot the longitudinal lines being so posititmed that, when the zero point ot the outer member is brought in registration With said mark, the 'traction indicated thereby will show the amount by which the tivo members have been relatively ially shifted `trom their initial or zero position.

Q. Means for indi 'at-inn' in common tractions ot' an inch the adjustment ot a micrometer, the sci-en' ot .vhich has the usual flll threads to the inch, said means compris ing tivo coaxial relatively rotatable cylindrical members, one being,l holloiv and telescoped on the other and the two being :interconnectt-ul through the gauge screw so as to be relatively shifted axially thereby in accord with the pitch ot the screw upon relative rotation ot the members,` the inner ot said members being;l provided upon its cylindrical si 'tace with eight lines extending longitudinally ot the cylinder and equally spaced therearoiuid, each ot' said longitudinal lines being;l provided ivith division marks, each ot said division marks being numbered to show the numerator ot the traction indicated thereby and the longitudinal lines being severally identilied with numbers correspondinp,- respectively to the denominator ot the fractions .indicated by the y marks hercon, the outer member being` provided at the end edge thereof overlying' the inner member with a zero mark and with a circumferential scale et graduations, the division marks of the longitudinal lines being,-

so positioned that said marks occur onlyY on every fifth longitudinal line taken in succession along the path traced by the zero l mark on the outer member at the ii'itersection oit said path.

3. As an article ol manufacture, a micrometer caliper comprisinga lixed sleeve and a rotary thimble surrounding and so connected with the sleeve as to be moved axially l/nlOth ot. an inch tor each complete revolution oft the thimble, the sleeve having' a longitudinal graduated line thereon and the thimble having an end edge :for registration with the graduations ot said line, said sleeve beingl provided with other longitudinal lines parallel With the graduated line and evenly spaced therewith around the sleeve and with transverse marks intersectinte' each of said longitudinal lines and located on a single imaginary helix around the sleeve, and designating directly at all times the exact distance in even multiples oit one 128th of an inch the distance of the end edge ot the thiinble from the zero point on said longitudinal scale, said thimble always covering and concealing the parts of said longitudinal lines overlapped by the edge o'l the thim'ble and said edge being provided with a Zero point for registration With said longitudinal lines.

at. As an article ot manufacture, a micrometer caliper comprisingl a relatively rotatable sleeve and thimble so connected that one moves axially on the other l/llOth ot an inch tor each complete relative rotation, the sleeve having a longitudinal graduated line thereon and the thimble having a reading edge for registration with the graduations of said line which edge is marked with a Zero point, said sleeve being provided with other longitudinal lines parallel With the graduated line and evenly spaced therewith around the sleeve, each ot' said longitudinal lines being divided into equal divisions by marks 1/ 8th ot an inch apart but leaving the end divisions of all the lines except the graduated line less than l/ Sth of an inch, the division marks being each numbered to show the numerator ot' the traction ot an inch by' which the spindle and anvil ot the gauge are separated when the said point of the thimble registers with such mark and the longitudinal lines being each numbered to correspond with the denominator of the iti-actions indicated thereon. y

Means for indicating in common :tractions of an inch the adjustment of a micrometer, the screw of Which has the usual lO threads to the inch, said means comprising tivo co-axial relatively rotatable cylindrical members, one being hollow and telescoped on the other and the tivo being interconnected through the gage screw so as to be relatively shifted axially thereby in accord with the pitch of the screw upon relative rot-ation of the members, the inner oi said members being provided upon its cylindrical sur'l'ace with eight lines extending longitudin-ally ot the cylinder, equally spaced therearound and all terminating in common planes perpendicular to its axis, each o't these longitudinal lines being provided with division marks spaced from one another by l/Sth of an inch but so distributed as to leave end spaces ditlerent for the diiicrent lines,

the end spaces ot' one line only being l/Sth ot an inch, those ot the others being less than that amount, each division mark being numbered to show the numerator of the fraction indicated thereby and the longitudinal lines being severally identilied with numbers corresponding respectively to the denominator otthe `fractions indicated by the marks thereon, the outer member being provided at the end edge thereof overlying the inner member with a Zero mark and with a circumferential scale ot graduations, each division mark of the. longitudinal lines being so positioned that, when the zero point ot the outer member is brought in registration with said mark, the traction indicated thereby will show the amount by which the two members have been relatively axially shifted from the position which they had when the zero point ot' the outer member registered with the initial or Zero division of that longitudinal line which is divided into eighths of an inch throughout it-s entire length.

In testimony whereof I have hereunto aiiiXed my signature.

RALPH G. ILSON. 

